1. Field of the Invention
This invention relates to coil handling apparatus and, more particularly, to a self-braking and self-tensioning coil reel.
2. Description of the Prior Art
Unreeling operations of coiled materials are often necessary in industrial situations. Telephone central offices, for example, use wire for making cross-connections on the main distributing frame and for similar applications. Coils of wire are mounted on a reel and wire is removed from the reel by pulling on the wire and causing the reel to rotate and unwind the wire. In order to prevent wire overrun and consequent entanglement and wastage of wire, a brake is provided on the reel for stopping the rotation of the reel when the pulling force is removed from the wire.
One type of wire reel brake, shown in J. P. Starace U.S. Pat. No. 3,796,392, granted Mar. 12, 1974, utilizes a resilient braking disk mounted to apply a braking force on the inner surface of the reel flange by the flat surface of the disk. The brake arm and shoe assembly is pivotally mounted on a base and is held away from the reel flange by the tension on the wire caused by the removal force as the wire is unreeled. Removal of this tension force allows the rotation of the brake arm assembly to bring the face of the brake disk against the inner face of the reel flange. Subsequent rotation of the reel wedges the braking shoe into contact with the flange surface to stop the rotation. The frictional braking force with this arrangement is determined by the disk material and cannot be adjusted.
Coils of wire for use with wire reels come in various thicknesses and hence an adjustable reel is desired for receiving such coils. Moreover, as the wire is removed from the coil, the coil configuration becomes shorter along its axis of rotation. Looseness in the coil wire on the reel permits the portion of wire being unwound under tension to become embedded in and bind in these loose coils, thereby interfering with the unreeling operation.
An adjustable reel is shown in J. E. Moore U.S. Pat. No. 3,830,445, granted Aug. 20, 1974, in which the two flanges are threaded together on a coil spring. Manual threading of the flanges together permits adjustments for various widths of coils and permits manual width adjustments during unreeling to maintain lateral tension on the coil. The spring provides a resilient lateral tensioning force. Such a reel, however, requires manual adjustment at various times during the unreeling operation.